Incorporation of insulating liners with the use of an article of clothing is known. As used herein, “clothing”, “garment”, or “article of clothing” includes not only under and outer wear (shirts, blouses, jackets, coats, pants, shorts, skirts, underwear, etc.), but also such things as footwear, gloves, blankets, sleeping bags, and other articles used to provide protection or comfort against the elements. Such insulating liners, when used in combination with the overlaying article of clothing, shield the user against uncomfortably cold or hot temperatures and high levels of moisture. Various insulating materials for insulating liners that have been used in the textile industry include felt, fleece, flannel, wool, various forms of latex foam, or the like. Although flexible and readily adaptable for textile applications, such materials are often provided in relatively thick slabs that can be bulky, thereby requiring the user to use, for example, a larger sized garment in order to fit the insulating insert or liner. Also, such materials often do not exhibit effective insulative properties in extremely high or extremely low temperature-related environments. Moreover, some advanced materials are designed to keep a user warm, like Thinsulate™, or dry, like GoreTEX™, but not both warm and dry.
Silica aerogels have been known to exhibit excellent thermal insulation performance and have been readily adapted for use in high temperature thermal insulation and cryogenic thermal insulation applications including, for example, advanced space suit designs by NASA. Aerogels, as that term is used herein, include polymers with pores with less than 50 nanometers in porous diameter. In a process known as sol-gel polymerization, monomers are suspended in solution and react with one another to form a sol, or collection, of colloidal clusters. The larger molecules then become bonded and cross-linked, forming a nearly solid and transparent sol-gel. An aerogel of this type can be produced by carefully drying the sol-gel so that the fragile network does not collapse. Thermal insulation blankets using aerogels have been developed, and aerogel materials are now commercially available in which the aerogel is impregnated or otherwise incorporated into a carbon or polyester based media.
One difficulty with using silica aerogels is that the aerogel tends to be dusty, even when supported by a carrier material. If the aerogel material is not properly contained and sealed within a liner assembly, the dust particles may escape the liner into the atmosphere thereby diminishing the effective insulative life of the insulating liner. Another difficulty with using silica aerogels is that an insulating liner assembly having aerogel may not effectively breathe or allow transfer of air and moisture between opposing sides of the liner.
Thus, it is an object of the present invention to provide an insulating liner for an article of clothing that effectively insulates against hot and cold temperature conditions, while reducing or even eliminating the loss of aerogel dust, yet allowing transfer of at least some air and moisture between opposing sides of the liner.